Coffee roaster



DeC- 2, 1952 R. J. GORMAN ET AL COFFEE ROASTER 2 SHEETS-SHEET l Filed Nov. 25, 1947 Patented Bec. 2, 1952 COFFEE ROASTER .Richard J. Gorman, Glendale, and Joseph W. .Binsacln Statenlsland, N. Y., `assi'gnors to Beech-Nut Packing Company,

Canajoharie,

. N. Y., a corporation of New York Application November 25, 1947,- Serial No. 787,978

(CI. 26S- 32) 3 Claims. l

This invention relates to coffee roasters.

The principal object of the invention is to provide a coiee roaster having novel and `improved means for controlling the operation thereof.

This and other objects of the .invention will become more apparent from the following Adescription and accompanying drawings, in Which- Fig. 1 is a side view, partly .diagrammatical, of a coffee roaster embodying the invention; and

Fig. 2 is a schematic View showing certain details of the control system thereof.

The coee roaster as illustrated includes an oven IG, a combustion chamber 26 and a particle collector `tank I5. Within the oven Ill is a roasting drum I I rotated by an electric motor I4 during the roasting process. For the purpose of loading and unloading coffee suitable means including a hopper IG and a housing Il communicating with the oven are also provided.

The heating means in this particular roasting equipment includes a premix blower 38 driven by an electric motor iii .and receiving gas from vthe supply line 30 for mixture with air and discharge through conduit tinto the combustion chamber 25. A continuously operated spark plug 42 having electrodes l and 4S within the conduit 39 insures ignition of the gas-air mixture. During the roasting operation air is circulated through the combustion chamber 26 and oven IU bygagblower 50 and motor 52. The air is withdrawn from the oven I@ through conduit I3, delivered to the collector I5 through conduit I9 and returned to the oven by the conduit 20 and combustion chamber 26. A pressure regulator 32 anda manually controlled valve 34 both located in the gas supply line 30 control the supply of gas to the pre-mix blower.

To operate the equipment individual electric switches Iii', lill and 52 are provided for controlling the motor I4, II!! and 52, respectively, and electric power for the spark plug d2 is obtained through the switch 4U' so that the spark plug will operate whenever the pre-mix.motor 4U is running. The temperature of the oven during the roasting process is constantly recorded on a temperature measuring and recordinginstrument 2l positioned just below the hopper I6.

Considerable difficulty has heretofore been experienced in the roasting of coffee with this conventional equipment, such as, for example, the

lack of uniformly good quality of coffee processed,

occasional damage to the equipment itself or certain parts of it and dangers to theV operating personnel.

In accordance with the present invention means are provided for ensuring uniform treatment for 2 successive coffee roasts whereby the gas supply is interruptedfin the event of failure of any one of the blowers Mor even extinguishment of the flame itself. Suppose, for instance, that Ythe cylinder motor IJ!! should suddenly stop. Under conventional `practice,..the llame would continue and `the surface layer of coffee in the drum would probably be burned in a relatively short time. With'this invention, however, vthe flame is immediately turned voif whilethe blowers remain in operation. This tends to reduce the temperature of `the oven and avoid any possibility of burning the coffee. Similarly, should the circulating blower motor 52er .the premix motor .so stop, the gas is again turned off, andthe remaining apparatus continues rv.to function normally. Means responsive to the gasflame are also employed to control the supply of gas so that sudden extingushment of the dame will immediately interruptthe gas supply and prevent the dischargeof unburned .gas into .the oven and chimney and thereby avoid endangering not only the apparatus itself but also personnel in the vicinity thereof.

As shown, `the controlcomprises time delay and oven starting circuits within the box 82, gas name `detecting .means 8d, a temperature responsive switch 4associated with, the temperature recorder 2l, .an .electrically operated gas valve 3E and relays responsive to the operation of the several vmotors I4, ll :andli which may be located with- -in a single housing 8d. These units are interconnected with each oth-er and with the motors by suitable electric conduits as illustrated. Each of the above relays is provided with contacts adapted to be closed when the switches II, lid' andp52 are closed to energize their respective motors and these contacts are connected in series rone with the other and with the electrically operated solenoid valve 36.

The'flame detector 80 and the time delay means :82 cooperate to actuate a fourth relay within the housingzg'. The contacts on this relay areconnected in series with the contacts on the above mentioned relays and all must be closed before energy will be transmitted to the valve 35 to admit gas to `the premiX blower 38 and combustion chamber 26.

,In starting the oven, closure of switches I4', 4.0' .and 52 will start their-respective motors operating and close the contacts and the relays in housing .82. A pushbutton |41 on housing 82 is then depressed to start the time delay system which .closes its associated relay contacts for a predetermined period of time. Closure of this last `set of relay contacts completes the circuit to operate the valve 36 and admit gas to the blower 38. Upon ignition of the gas in the combustion chamber and response of the photoelectric flame detector 80, the latter will independently operate the relay in the housing 82 so that gas will continue to flow through valve 36. Should, however, the gas fail to become ignited the relay will automatically open after the predetermined time and close the valve 36.

From the above description it is apparent each of the electrically operated parts of the oven must be in operation before gas can be admitted into the combustion chamber for ignition and if the llame becomes extinguished or the power to any one of the motors fails, one or more of the relays will open to interrupt the supply of gas.

Means are also provided in this control system to limit the temperature of the oven and includes a switch associated with the temperature indicator 2| adapted to open when the temperature reaches a predetermined value. This switch is connected in series with the coil of one of the relays and causes the relay to open when the temperature reaches the predetermined value. In this way a coffee roast cannot be subjected to excess temperature and uniform treatment will be accorded successive roasts. Moreover, since the gas is immediately interrupted upon failure of one of the motors or extinguishment of the flame, damage to the roast, the equipment or danger to personnel will be avoided.

This control system as well as the several motors and ignition systems receive electric power from a three-phase alternating current source connected with the conductors 86.

The cylinder and insulating blower motors i4 and 52, respectively, are of the three-phase alternating current type and are connected through triple pole single-throw switches I4 and 52 and appropriate fuses to the supply conductors 66 while the premix motor 46 is a single phase motor and is connected through its switch 40 and fuses to only two of the conductors 86. Since in the present arrangement the gas igniting means or spark plug 42 is to be operated continuously, the transformer 8l supplying ignition voltage to the spark plug has its primary 6l connected directly across the leads supplying the motor 46 so that both the motor lli) and the spark plug 42 are operated simultaneously by closure of the switch 40. The transformer Sl is of conventional construction and has a high voltage secondary 8l having one side connected to the terminal la of the plug 42 and the other side connected to the base or ground side of the plug l2 by the use of suitable ground connections.

Associated with the motors Ill and 52 are single pole, single-throw relays 68 and 89, respectively, the coils of which are connected across two of the three connectors supplying their respective motors and operate to close their contacts 88a-83b and BSc-89h when the switches I4 and are closed to energize the motors. A relay 36 having contacts 96a and 90b is connected in series with a switch 3| housed within the temperature control mechanism 2| and operable to open when the temperature exceeds a predetermined maximum, is connected in parallel with the primary 3l' of the transformer 81 by leads 92 and 93 so that when the premix motor switch 46' is closed to energize the premix motor 4|] and the primary winding 8l of the transformer 8l the relay coil 9D will also be energized to close its contacts 96a and 96h. A fourth relay 94 within the control box 82 operates in response to the photoelectric mechanism to be described to close its contacts 94a and 94h.

For normal operation of the oven, each of the relays 88, 89, and 94 must be actuated to energize the solenoid valve 36 so that it will open and admit gas to the premix blower 38. The circuit for accomplishing this action includes a lead 95 connecting one side of the winding 81 to one side of the solenoid valve winding 36 of the valve 36, and the lead 96 connecting the other side of the valve to the relay 66a. The remainder of this circuit consists of a series arrangement including contact 6Go, lead 9T, relay contacts 89a and 89h, the lead 98, relay contacts 88a and 88D, the lead 99, relay contacts 94a and 94h, and the leads |00 and |0| to the other side of the primary winding 8l of the transformer 31. Only under the condition, therefore, where each pair of relay contacts referred to above is closed will the valve 36 be operated to open and permit the supply of gas through conduit 39 to be ignited and heat the oven.

As previously mentioned, a photoelectric eye is arranged to view the heating flame in the cylindrical housing 26 and is contained within the box 63 and is denoted in Fig. 2 by the numeral |03. The response of the electric eye is amplified by the tube |16 and operates to actuate the relay 94 as will become apparent.

More particularly the cathode |34 of the tube |63 is connected directly to the control grid |65 of the amplifier tube |66, and its anode |91 is connected to the center terminal of a pair of series connected resistors |68 and |09 which are connected in parallel with a filament voltage dropping resistor H6. The upper terminal H0 of the resistor H6 is connected to the lead |6| which, as previously described, connects with one of the supply conductors 86. The other side of the resistor H6 is connected by means of lead to a rheostat H2 which in turn connects with the cathode H3 to one side of the filament H4 of the tube |66. The other side of the filament H4 is returned to one of the other conductors 86 by means of the leads H5 and H6. Since the leads lill and H6 supplying the electronic circuits in the boxes 86 and S2 are connected to the winding 8l', the supply of energy to those circuits is under the control of switch 40'.

The cathode H3 of the amplifying tube |06 is connected to one side of filament H4 and then to the lead H5 through a resistor H6 and a potentiometer H7. The grid |65 is connected to the tap on the potentiometer through a resistor H8 so that the bias on the grid |65 can be adjusted for proper operation of the tube |06. The tube |66 is operated as a triode with its suppressor grid H9 and its screen grid |25) connected to the plate |2|, and the plate circuit including the plate |2| is completed through the lead |22, milliammeter |23, the relay coil |24 and the lead |25 to the conductor ISI. A condenser |26 is connected between the leads |22 and |25 to filter the voltage applied to the D. C. relay |24 since the current in the plate circuit of tube |06 is of a pulsating character because of the use of alternating current in the plate circuit thereof.

Under normal operation of the oven the flame produced by combustion of the gas in the cylinder 26 creates suiiicient light to actuate the photocell |03 and cause the tube |66 to draw current in its plate circuit. This current is registered on the milliammeter |23 and is also suiiicient to actuate the relay |24 to close its associated contacts.

During the normal operation of the device wherein the tube |33 is operated by the photocell |03 to close the relay contacts |2ld and l2lb, a circuit is completed from the lead |25 through the contacts |24@ and |245 through lead |26, the relay coil 35 and lead |21 to the other side of the power supply H5. rlhis actuates the relay 3d to close its contacts and, assuming the other relay contacts connected in series with the contacts 34a and 33h are also closed, gas will be continuously delivered into the conduit 33. A pilot light |23, connected in parallel with the relay coil 00, produces a visual indication i the actuation of the relay 03.

The time delay starting means for the oven. whereby gas is delivered to the supply conduit 33 for ignition and operation of the photooell |33 includes a gas-filled Thyratrcn tube |30 located in the control box 32. The lament |32 of this tube is heated by a suitable filament transformer |3i having its primary |3l connected between the voltage supply lines itl and M and its secondary ii" connected to the iilament |32. An A. C. relay |33 is connected in series with one ci the filament leads to the lament |32 and operates to close its contacts |33c and |335 when the filament is energized. The plate circuit oi the tube |30 includes a plate |34, a series resistor |35 and a relay |33 and lead |31 to the supply line or conductor lill. A condenser |33 is connected in parallel with the D. C. relay |36 and operates in a manner similar to condenser |23 in that it smoothes the intermittent plate voltage of tube |30 operating the relay |36. The screen grid |39 is connected to the supply lead |33 through a series resistor |40, a lead lill and lead |33. The cathode 4| of the tube |30 is connected in the first instance to the screen grid |33 by the lead |32 and is also connected through the lead |32' to the A. C. relay |43. The other side of the relay |43 is connected through the lead U34 through the normally closed contacts |3531, and |335 of the relay |36 and through leads M5 and 531 to the supply conductor 50|. The completion of the circuit for cathode l-i to the supply conductor H5 is accomplished through the lead |46, the pushbutton switch lill and lead |40 so that closure of the switch 31 to complete the cathode circuit will also actuate the relay M3 to close its normally open contacts w3c-|432) and l43c-lfl3d. rThe control grid |50 of the Thyratron tube |30 is connected through a series resistor |5|, the lead |52, and a second series resistor |53 to the contact arm i565 of the switch |55. The switch |55 includes -two contacts |53 and |51 having a resistor 53 connected therebetween. The switch contact |56 is connected to the supply lead H5 by the lead |53. It is evident therefore that the grid |53 may be returned to ground through a series connection oi the three resistors |5|, E53 and |58 by settingr the contact arm |54 on the contact l5'l, or in the alternative7 by setting the contact arm 53 on the contact |50 the return to ground can be accomplished merely through a series connection of the resistors |5i and |53. A condenser |60 is connected between the lead |52 and supply conductor H5'. The relay contacts ILE-3d and |431) are connected by means of the leads itl and |42-|45 to bridge the push-button |4l. The contacts ilic and |43d are connected in series `with the contacts |33a and |335 oi the relay |33 by means of the 6 lead |02 .and these two sets of contacts .arecon nected'to bridge the contacts 1240i and |245 of the relay |24 by means of the leads |63 and |63.

Since the operation `of this time delay mechanism will best be understood in connection with the operation of the device as a Whole, We will now describe in detail the procedure for starting and operating the oven.

yThe switches 40252 and I4 are i'lrst closed. These switches Ystart their respective motors and energize the relays .associated therewith to close 4their respective contacts. For instance, closure of the switch 40 will energize the premix motor, the ignition transformer 81 and the A. C. relay 90 through the temperature control contacts 9|, andclosure of the switches 52 and I4 will operate the relays 89 and 83, respectively, to close theircontacts. Closure of the switch 40. as previously described, will also energize the control circuits in the box and B2, heating the lilament ||4 of the tube |06 and the lament |32 of the tube |30. Heating lament |32, as previously `pointed out, will also actuate the relay |33 to close its contacts |33a and |33b. Since there is no v'flame in the heating chamber 26 the electric eye |03 will not be actuated and, therefore, relay |24 will remain open. Since the contacts |43c and |43d on the relay |43 are also open, a circuit is not completed through the relay 94, and, therefore, its associated contacts 04a and 9419 will also remain open.

It isapparent that although the relays 88, 89 and90 have been actuated, relay 94 must also beactuated before the solenoid 36 on the valve 36 can be energized to open and admit gas into the conduit 3,9.

The next step in initiating the operation is to open the manually operated valve 35. To operate the valve 36 so that gas will be admitted to the premix blower 30 the pushbutton |41 is closed, energizing the relay |43 through the contacts |36a and |3612 of the relay |33. Since the contacts |4311 and |435 short circuit the switch |41, momentary pressing of the switch or pushbutton |41 is all that is required since these contacts then act as holding contacts for the relay. Contacts |430 and |43d are also closed through energization of the relay |33, and a circuit will be completed from lead |0|, leads |25 and |63, lead |62, the relay contacts |4305 and |43d, the lead |64, the relay 54 and the pilot light |28 in parallel and lead |21 to the other supply conductor ||5. This will energize the relay 94 to close its contacts and complete the circuit to the solenoid valve 36, causing it to open and admit gas into the conduit 33. Since the cathode circuit of the tube |30 is also completed to ground by closure of the contacts |43a and |435, the tube |30 is placed in an operating condition.

The tube |30 is arranged in a time delay circuit and functions after a predetermined interval after pressing of pushbutton |41 to draw plate current and actuate relay |36 to open its contacts and deenergize control relay |43. This is accomplished by resistors |53 and |58 in combination with the capacitor |50 to determine the time when a given grid voltage is applied to the tube |50 and cause it to draw its maximum plate current. Since a Thyratron tube can be said to have only two operating conditions-that is, a condition where it draws maximum plate current and a condition Where it draws a negligible amount of plate current-it is only necessary to control the time in which the critical grid voltage is applied to the grid to cause it to change from a condition of nonconduction or minimum plate current to a condition of conduction where it draws its maximum plate current. As mentioned, this time is controlled by the relationship of the resistors |53 and |58 to the condenser |60, and for. present purposes has been adjusted to give a delay of one second when arm |54 is on contact |51, and two seconds when arm |54 is on contact |56. Assuming they arm |54 to be on contact |51, a time delay of about two seconds will be obtained before the tube becomes conducting to actuate the relay in its plate circuit.

After the pushbutton |41 has been operated to close the contacts on relay |43 the gas is permitted to enter the cylindrical chamber 26 for a period of time determined by the time delay characteristics of the grid circuit ofthe grid |30. When the voltage on the grid |50 has attained or passed its critical value, the tube |30 becomes conducting and draws current through coil |36 and the resistor |35. This actionv operates to open the relay contacts |36a and |36b and deenergize the relay |43, whereupon its associated contacts are opened. As previously pointed out, the contacts |43c and |43d in series with the contacts |33a and |331) of the relay |33 are connected across the relay contacts |24a and |241) of the relay |24. If during the time immediately following depression of the button |41 but prior to the time that the tube |30 becomes conducting, the gas emitted in cylinder 26 for heating the furnace has been properly ignited by the spark plug 42 and the photocell |03 has responded to such ignition and burning so as to cause the tube |06 to draw plate current and actuate the relay |24 to close its associated contacts, then the opening of the contacts |43c and |43d of the relay |43 will not operate to deenergize the relay 94, the contacts of which are in the control circuit of the gas valve 36.

However, should the gas fail to ignite within the time delay period, the contacts of relay |24 will remain open, and opening of the contacts |43c and |43d will deenergize the relay 94, whereupon its contacts will open and deenergize the solenoid 36 toy close the valve 36 against further delivery of gas to the conduit 39. Since each of the several elements in the electronic circuit must be actuated to provide a continuous supply of gas it is apparent that failure of any part of the circuit or of the voltage supplying any one of the individual motor circuits will immediately act to interrupt the gas supply so that no damage to the material being treated will be incurred. For instance, if the photo tube |03 fails to operate, relay |24 will immediately be deenergized. A similar reaction will occur if, for instance, the filament current is interrupted in the nlament ||4 of the tube |06 by reason of failure of the filament itself or the associated voltage dropping resistors. Likewise, if the filament |32 burns out for any reason or the voltage supply fails, the relay |33 will be deenergized and it will be impossible to restart the furnace if for any reason the gas supply is interrupted until, of course, the tube is replaced. Furthermore, during the operation of the furnace, if the temperature should exceed a predetermined value, the switch 9| associated with the temperature indicator 12 is arranged so that it will open, break the circuit to the relay 90 and deenergize that relay. This will Vcause its contacts 90a and 90b to open, and since they are n the control circuit operating the solenoid gas valve 36, the gas supply will be interrupted and the heating process will be immediately stopped.

By the foregoing invention, proper starting as well as proper continued operation of the roaster after it has been started is ensured, since the Various electrical control devices employed are arranged so that either failure of those devices or of the roaster motors will interrupt the supply of gas and thereby immediately indicate to the operator that some part or parts have failed. Because the circuits are arranged in the manner described predetermined steps must be followed in starting the oven, so that it is impossible to omit any one or more of the steps in the starting procedure which might result in damage to the coffee being treated. This is particularly important in roasting coffee because a batch or roast can be Very quickly and easily burned by omitting, for instance, td turn on the circulating blower prior to ignition of the gas. The device also maintains, a constant check on the temperature of the oven and the gas flame and immediately causes the gas to be turned off in the event of any departure from normal or desired operation.

Having described my invention, what is claimed 1s:

l. A roaster of the class described comprising an oven and a combustion chamber, means ncluding a premix blower and electric motor for mixing combustible gas and air and discharging it into the combustion chamber, an electric motor driven blower for circulating air through the combustion chamber and oven, temperature indicating means on said oven, a motor driven roasting cylinder Within the oven to hold the coffee to be roasted, and means including a spark plug and transformer for igniting the gas in the combustion chamber, in combination with control means comprising a normally open relay connected with each of said motors and operable to close its contacts upon the application of energy to its associated motor, said relay associated with said premix motor being connected with the temperature indicating means, an electric eye including an amplifier tube positioned to View the ignited gas, and at least one normally open relay associated with said tube and operable to close its contacts upon detection of the heating flame by said photocell, a solenoid valve in said gas supply, a series connection between the contacts on each of the aforesaid relays, and the solenoid gas supply valve so that upon operation of each of said normally open relays the valve will be energized to open and admit gas to the oven, time delay means having at least one relay and operable upon the initiation of said heating process to actuate the contacts on said photocell relay and permit gas to be discharged into the combustion chamber and ignited by the spark plug whereupon ignition of the gas and response of the photocell thereto to actuate its associated relay will maintain the contacts in the closed position and permit gas to flow without reliance on the time delay device.

2. A roaster of the class described comprising an oven, a combustion chamber associated with the oven, means for suppyLing fuel to the combustion chamber having a control valve, separately operable means for feeding air to the combustion chamber and for agitating the contents of the oven, manually operated means for separately throwing said feeding and agitating means into operation, temperature control means for operating said valve to interrupt the fuel supply upon the attainment of a predetermined temperature in the oven, in combination with means acting automatically to open said valve to supply fuel to the combustion chamber upon both of said air feeding and agitating means being thrown into` operation and to maintain said fuel valve open contingent upon the ignition and continued burning of the fuel and the continued operation of the feeding and agitating means.

3. A roaster of the class described comprising an oven, fuel supply means including a valve and circuit therefor operable to control the flow of fuel to the oven, a plurality of separately controlled means associated with the oven including fuel ignition means, air feeding and circulating means, and agitating means for the coffee to be roasted, and temperature control means connected to said valve to interrupt the fuel supply upon the attainment of a predetermined temperature, in combination with individual means responsive to said manually controlled means and connected to the valve, said individual means being operated upon initiation of its associated controlled means, a combustion responsive device REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,824,057.l Robertshaw et al. Sept. 22, 1931 1,945,652 Martin Feb. 6, 1934 2,081,091 Kumpel May 18, 1937 2,092,657 Smith Sept. 7, 1937 2,201,385 Woodson May 21, 1940 2,396,898 Storme Mar. 19, 1946 

